Interstellar medium disruption in the Centaurus A group.
BOUCHARD A., JERJEN H., DA COSTA G.S. and OTT J.
Abstract (from CDS):
We present the results of a 21 cm neutral hydrogen (H I) line detection experiment in the direction of 18 low-luminosity dwarf galaxies of the Centaurus A group, using the Australia Telescope National Facility 64 m Parkes Radio Telescope and the Australia Telescope Compact Array. Five dwarfs have H I masses between M_HI_=4x105 and 2.1x107M☉and 0.04 M☉L–1☉,B<M_HI/LB_<1.81 M☉L–1☉,B. The other 13 have upper limits between M_HI_=5x105 and 4x106M☉ (M_HI/LB_<0.24 M☉L–1☉,B). Two of the mixed-morphology dwarfs remain undetected in H I, a situation that is in contrast to that of similar Local Group and Sculptor group objects, which all contain significant amounts of neutral gas. There is a discontinuity in the H I properties of Centaurus A group low-luminosity dwarfs that is unobserved among Sculptor group dwarfs. All objects fainter than MB=-13 have either M_HI_>107 or M_HI_<106M☉. This gap may be explained by the ram pressure stripping mechanism at work in this dense environment in which all galaxies with M_HI_<107M☉have been stripped of their gas. The required intergalactic medium density to achieve this is ∼10–3/cm3.
Galaxies: Dwarf - Galaxies: Evolution - Galaxies: Individual: Name: Centaurus A - Galaxies: ISM